16 ideas
| 9193 | ZF set theory has variables which range over sets, 'equals' and 'member', and extensionality [Dummett] |
| 9194 | The main alternative to ZF is one which includes looser classes as well as sets [Dummett] |
| 9195 | Intuitionists reject excluded middle, not for a third value, but for possibility of proof [Dummett] |
| 9186 | First-order logic concerns objects; second-order adds properties, kinds, relations and functions [Dummett] |
| 9187 | Logical truths and inference are characterized either syntactically or semantically [Dummett] |
| 9191 | Ordinals seem more basic than cardinals, since we count objects in sequence [Dummett] |
| 9192 | The number 4 has different positions in the naturals and the wholes, with the same structure [Dummett] |
| 19419 | Not all of perception is accompanied by consciousness [Leibniz] |
| 19421 | Souls act as if there were no bodies, and bodies act as if there were no souls [Leibniz] |
| 19420 | Death and generation are just transformations of an animal, augmented or diminished [Leibniz] |
| 13304 | Learned men gain more in one day than others do in a lifetime [Posidonius] |
| 19416 | Not all of matter is animated, any more than a pond full of living fish is animated [Leibniz] |
| 19422 | Every particle of matter contains organic bodies [Leibniz] |
| 20820 | Time is an interval of motion, or the measure of speed [Posidonius, by Stobaeus] |
| 19418 | Mechanics shows that all motion originates in other motion, so there is a Prime Mover [Leibniz] |
| 19417 | All substances are in harmony, even though separate, so they must have one divine cause [Leibniz] |